Tube bender



Dec. 21, 1948. C. J. CHAILLI': 2,4s6,675

I TUBE BE'NDER Filed Jan. 25, 1947 2 Sheets-Sheet 1 Dec. 21, 1948. c. J.cHAILLE 2,455,675

TUBE BENDER Filed Jan. 25, 1947 2 Sheets-Sheet 2 from-frn;

the respective I-beams. The bending dies -20 are designed to swing openin opposite directions as the forming die [6 advances, and the rockingmotion of the dies is resisted by a pair of compression Springs 21-21,one for each bending die.

Compression Springs 21 are carried respectively upon shafts 28, theforward end of each shaft including a. block 3| forming part of theshaft. These blocks in turn are Secured to a backing plate 33, whichplate bears against the rear surface of dies 20. Plate 33 thus forms abearing block which, as the bending dies are forced open, engages theswinging edges of the respective dies to spring load them. In thismanner the dies back up the tube against the4 pressure of the advancingforming die. g p

In order to stabilize and guide the plate 33 and shafts 28, the rearwardends of the respective' shafts are slidably engaged in a bearing elementgenerally indicated at 35. This element constitutes spaced bearingflanges each having a pair of aligned holes to slidably sustain arespective shaft 28. As shown in Figure 1,y element includes an anglebracket 40 having a vertical limb 4|k and a horizontal limbf42 seatedand secured upon the upper web of the respective I-beams l I. A T-shapedmember 43 having a horizontal Web 44 secured by welding or other meansto the web 42 of angle member 4l, supports the rearward endsof'th'e'shaft 28, while the vertical flange 4| of angle piece 40supports the forward'portion of the shafts. f It will be apparent thatthe spaced relationship of the bearing plates 4| and 43 prevents bindingof the shafts 28 therein which otherwise might occur; due to lateralforces against the forward ends of the shafts developed in the'slidingof'plate 33 relative to the vhinged bending dies 20-20.

The compression'springs 21 have their rear- Ward ends seated against aplate 36 secured to flangei4l of the angle piece 40 while their oppositeends a're seated against the blocks 31. Upon advance of the ram l4carrying forming die IG, as *shown vin Figure 5, plate 33 will be forcedrearwardly thereby compressing Springs 21 between the blocks 3! and theplate 36. When' the ram reaches the limit' of its stroke it tripscontrol valve lf:l as hereinafter described, stops automatically andretracts 'to its starting position. When this occurs the springs2'l,bearing against bending dies 20, causethe bending dies 'to follow theforming die tolreturn' them to their normal position as shown in Figure3. This causes the formed tube to be ejxec'ted automatically from thedies. Thev tube may be permitted to dropV into a chute or container orit may be grasped by the operator for manual removal.

' As viewed in Figure'z, each bending die' 20 includes at .one end apair of lugs 45-45. The inner end of the respective pivot pins 2! areengaged in these lugs and the lugs thus provide an open throat 45 toreceive the tube without interf'erence with the pivot pins. In otherwords, the pivot pins 2I do not extend across the dies since this wouldinterfere With the placing of work in the diesfor in its removaltherefrom'. g Referring to'Figure 1, the louter ends of the pivot 'pins2l are engaged in lugs4l, the lugs being secured to the plate23,'preferably by welding .V Lugs 41 each include a bore 48 toreceivethe pivot pins and to permit the pivot pins to be withdrawn whenit is necessary to remove the bending' dies from the machine tobeinterchanged with dies of a different size as hereinafter described,

It will be notedthat theforming vdie is of Kil lf ormn'g dies which aresupplied with appropriate grooves 5!!v c'orrespoding tofthe'desiredpipeor tubejdiametersl Likewse,fjshould. it be desiredsemi-circular face contour as viewed in Figure 3 and that the flat facesof the bending dies 20-20 contact the periphery of the forming die whenit advances. The advance of forming die IG causes the bending dies 20-20to rock open in opposite directions by means of their pivotal mountingstuds 2| as shown in Figure 5. As viewed in cross section (Figure 4) theforming die and bending dies each are provided longitudinally with asemi-circular groove 50 complementary to each other to provide acircular recess conforming to the diameter of the tube to be bent andclosely embracing it. Since the Swinging dies 20 contact the peripheryofforming die [6 at a moving tangential line of contact during thestroke,-the tube is completely enclosed in the bending zone. In otherwords, the tangential line of contact, as indicated at 51, is located inthe bending zone and since the bending operation is progressive,starting at the parting line 52 of dies 20 and working outwardly inopposite directions, the line of contact'progresses with=the bendingzone. It has been found that this .arrangement substantially eliminatesdistortion and fiattening of the tube. Since the dies completelyen'circle the tube in the bending zone,- itisprevented from expandinglaterally o'fi'the bend as normally occurs. Apparently this causes themetal to flow sufficiently to accommodatethe differential betweentheinside and outside radius of the bend, producing a swagingfeffect.greatly improving the quality of the work.

It will be apparent that during Vthe' bendingL operation thetube isrigidly. supported at its opposite ends by the vpivot pins 2|,"whichsupport the bending dies IG, although theiiends of the dies areyieldable. As the forming Ldie, advances', the tube begins to bend atitsce'nter outwardly in opposite directions progress'infg toward thepivot pins as the bending dies lfivsw/'in'gli'n opposite directions.Therefore, the major bending forceis resisted by the pivot pinswhilefthe pressure exerted by'springs'Z'I serves 4tofmaintain thebendingdies against the forming die toen- 'close thev tube in thebendingv zone.

The. apparatus is capable of bfnclingtubin'g'forl pipes lof'the severalstandard' commercial sizes ranging for example from 1/4 to1 1/2"- in.diameter and in wall thick'nesfsV up to 1/8. vThis is accomplished byinterchanging the bending and to bend'the tube to a smaller or largerradius an forming die IB having-the desired appropriate :face 'radiusmaybeinstalledin the-ram..l ,It.will

be apparent*- ofy course that the'radisofjthe finished bend will conformto the radius, of forming die l'aslshown in Figure 5.

As previouslyl noted the .angleI of the-bendfis regulated byadjustin'g'the advan ef or forward stroke of the forming die IGrelative'to the bending dies. In otherL words, accmplete "return lourU-shaped bend may be formed by causing"v Ithe ram to advancesufiicientlyv to causefltheiline vc'cintact of the bendingfdies torea'chlth'el center line .of'the semi-circular'forming die,andconversely,

theangle-of the bend may be reduced by limitin'g theadvance of die" l.Adjus'ting meanslare provided which may be rgulatedto's'top thei'ad-Vance accurately atapredetrmined position;

For this. purpose a control rod 55l xtendsforwardlyfrom the controlvalve 15, having* a'fstop collaru adjustably Secured' on its. forward'end.

.ThissOllafPQOPGFeieS: time-OP .51 Ferries-Py afizsaevzs ram M. Stop 51oonstitutes a ring 58 engaged on the forward end of the ram and includesa laterally extending arm 59, the outer end of which includes a boss orhub 60 having a bore through Which rod 55 is slidably projected. Therearward end of control rod 55 is slidably mounted in a U-shaped bracket6| Secured to the top of the hydraulic control unit 15.

The hydraulic control unit serves as a reversing valve to control thesupply of hydraulic pressure to the cylinder |2 and includes a handoperated control lever 62. As shown in Figure 3, the control lever isshown in dotted lines in its normal or ram retracting position and isshown in full lines in its ram advancing position. This lever ispivotally mounted as at 63 upon control shaft 64 so as to permit thelever to be rocked in a lateral direction with respect to the U-shapedbracket BI. Bracket 6l includes a notch 65 along its side edge intowhich the control lever 62 may be engaged. When the lever is swung tothe position shown in Figure 3, in engagement in the notch 65, hydraulicpressure is conducted to the cylinder l2 to cause the ram to advance.The advance of th e ram continues until stop hub 66 engages collar 56secured to the end of control rod 55. Upon engaging the stop collar, thecontrol rod is caused to move forwardly with the ram, compressing spring66 which is seated between bracket 6l and collar 61 secured t-o the rearend of the control rod. Forward movement of the rod causes the camsegment 68, secured to control rod, to engage control lever and move thesame laterally out of engagement with notch 65. When this occurs,tension spring 10, having one end anchored upon bracket 'Il and itsopposite end anchored to control lever 62, causes the control lever tosnap forwardly to its reversing position whereupon the supply of fluidpressure to the cylinder is reversed causing ram 14 to retraot. Thismotion will continue until ram M reaches its fully retracted position asshown in Figure 1 whereupon the cycle of operation is ended. It will beapparent, therefore, that adjustment of collar 51 relative to thecontrol rod 55 limits the bending motion of the ram and by so doingregulates the angle to which the tubing is bent. In order to provide afine adjustment the control rod 55 may be screw threaded at its forwardend as at 12 to permit the collar to be adjusted accurately with respectto the rod and may be looked in adjusted position by means of set screw13.

The machine is operated by placing the pipe or tubing in position in thebending dies as shown in Figure 1, preferably by the provision of asuitable fixture or stop to position the tubing length- Wise relative tothe dies. Valve control lever 62 is then rocked manually in a rearwarddirection to engage the shank of the lever 62 in notch 65 to cause theram M to advance. The cycle will then continue until hub 60 engagescollar 56 to trip the control rod and cause reversal of the ram.Hydraulic pressure is conducted to the valve |5 from a pressure supplysystem and from the valve to the forward and rearward ends of thehydraulic unit |2 by means of the tubes 14 and 15. Valve I 5 is arrangedalternately to supply one or the other of these lines to cause theappropriate ram motion.

It will be noted that having once been adjusted, each succeeding workpiece will be identical as to angularity and radius since the advance ofthe die is uniform for each work piece as controlled by the stop collar516. Therefore, the apparatus produces work of uniform proportions tomeet the required production standards.

Having described my invention, I claim:

1. A tube bending apparatus comprising, a frame, a hydraulic cylinderand ram unit mounted upon said frame, a forming die carried by said ramand adapted to be advanced and retracted by said ram, a pair ofstationary bending dies yieldably mounted upon said frame andcooperating with said forming die, a valve for controlling the advanceand retraction of said ram and forming die relative to the bending diesto bend the work to a predetermined angle, a manually operated lever onsaid valve for initiating the advance of the ram, an adjustable tripmechanism associated with said manually operated lever, and a stopelement carried by said ram cooperating With said trip mechanism andarranged to actuate the trip mechanism to reverse the position of saidmanually operated lever and cause the ram to vretract When the formingdie bends said Work to a predetermined angle.

2. A tube bending apparatus comprising; a frame, a hydraulicallyactuated ram carried by said frame, a forming die carried by the ram andadapted to be advanced and retracted by the ram, a pair of stationarybending dies mounted on said frame and arranged to engage the oppositeends of a tube to be bent, said die disposed in alignf ment and havingtheir respective opposite ends pivotally mounted and adapted to open inopposite directions, said forming die having a curved face to determinethe radius of a bend and adapted to engage an intermediate portion ofthe tube, said bending dies having straight faces adapted to engage thecurved face of the forming die to provide a progressive bending zonestarting at the center of the forming die and progressing outwardly inopposite directions, whereby distance advanced by the forming dierelative to the bending dies determines the angle between the oppositeends of the tube, spring loading means on said bending dies to exert abending pressure against said forming die, a reversing valve having acontrol lever and adjustable stop means adapted to be contacted by saidram at the end of its stroke, said stop means carrying a cam forengaging said lever and actuating said reversing valve whereby said ramis automatically reversed when said tube is bent to a predeterminedangle.

CHARLES JOSEPH CHAILLE.

REFEREN CES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 926,093 Brown June 29, 19091,610,196 Blaisdell Dec. 7, 1926 1,948,474 Meyer Feb. 20, 1934 2,246,379Muir et al June 17, 1941 2,335,809 Stacy Nov. 30, 1943

